1. Field of the Invention
The invention covers a method for preparing slurries of soda ash and water and the apparatus for effecting these slurries.
2. Description of the Prior Art
It is known that soda ash can be stored and dispensed in the form of an aqueous mixture. Upon mixing sufficient soda ash with water at temperatures greater than 35.degree. C., part of the soda ash dissolves to form a saturated sodium carbonate solution while the remainder, which does not dissolve, is converted to particles of sodium carbonate monohydrate that settle to the bottom of the mixture as a fluid, non-hardening slurry.
This method of storage is desirable because the slurry has a considerably higher apparent density than the dry soda ash from which it was made. As a result it is possible to store up to twice the soda ash in a given volume as a slurry rather than in its dry form. The soda ash is recovered from the storage tank by removing the upper layer of saturated soda ash solution. In many cases the uniformity of the saturated soda ash solution permits dispensing of the soda ash volumetrically with acceptable accuracy. Typical methods for storing and withdrawing of soda ash slurries are described in U.S. Pat. Nos. 3,357,801; 3,802,848; 3,891,393; 2,024,830; and 2,043,710.
The soda ash is replenished in the storage tank most conveniently by mixing soda ash (conveyed via air) and water to form a slurry using some sort of injection device, as for example a nozzle. This method of addition increases the amount of both saturated soda ash and sodium carbonate monohydrate crystals in the storage tank.
Several difficulties are associated with these known methods and apparatus for slurrying soda ash. For example, one of the difficulties which has arisen in these systems has been in slurrying the soda ash properly with water or an aqueous sodium carbonate solution prior to introducing the soda ash into the storage tank without clogging the slurry injecting device. Prior art nozzle designs permit contact of the soda ash and solution as early as the end of the nozzle. This results in a build-up of wet, caked soda ash at the end of the nozzle, and plugging of the air-soda ash line results. This necessitates frequent shut down for unclogging purposes and increases process cost. As a result, it is desirous to develop a process and apparatus for forming and injecting soda ash slurries into storage tanks which alleviate the clogging problem.